Black/African American Women (BAAW) are at elevated risk for HIV/AIDS through both heterosexual transmission and drug-related risk behavior. In San Diego County, California, BAAW account for 26% of all female HIV cases, despite only being 5% of the County population and the AIDS rate are almost eight times higher among BAAW in San Diego County than among white women. In response to RFA-DA-14-010, HIV/AIDS and Substance Use among Black/African American Women and Young MSM, we will evaluate how BAAW's social network structure, social norms, and experiences and behaviors of influential social network contacts are associated with HIV status, HIV risk behavior, and history of HIV testing. In this innovative social- network study, we will use egocentric network methods to assess three levels of influence: 1) women's own behaviors, beliefs, and experiences, 2) the structure/composition of women's personal social networks and women's perceptions of their network member's behaviors, beliefs, and experiences, and 3) the actual behaviors, beliefs, and experiences of influential network members. The proposed study has the following specific aims: 1. Evaluate how social, sexual, and drug use network factors (e.g., network size, structure, composition, perceived norms) are associated with substance use, HIV risk behavior, and HIV testing among BAAW. 2. Determine the association between cultural beliefs, experiences, and behaviors of BAAW's network members and the behavior of BAAW, and determine accuracy of BAAW's perceptions of their network. 3. Identify targets for a social network intervention for BAAW designed to decrease risk behavior and increase uptake of HIV testing, and use qualitative focus groups to determine the acceptability and cultural appropriateness of a network-based intervention strategy. The proposed study also has the following exploratory aim: 4. Investigate the social network factors associated with HIV status and linkage to and retention in care among HIV+ BAAW. To accomplish these aims, we propose a mixed methods social network study with 100 at-risk, self-reported HIV-negative BAAW in San Diego, California and up to 500 of their social network contacts (total N=600). In Phase I we will use surveys and egocentric network interviews to assess individual and network characteristics reported by BAAW and their networks. In Phase II we will conduct focus groups to assess the acceptability of a social network-based intervention involving influential network members. The proposed research will advance the President's National HIV/AIDS Strategy to reduce new infections, increase access to care, and reduce HIV-related health disparities.